Apparatus for manufacturing piston-rings



F. RAY.

APPARATUS FOR MANUFACTURING PISTON RINGS.

APPLICATION FILED OCT-12.1918.

Patented June 1, 1920.

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I HVI/ElI/TOR APPLICATION FILED OCT- I2, I9I8- Patented June 1, 1920.

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APPARATUS FOR MA'NUFACTURING PISTON RINGS.

APPLICATION FILED OCT-A2, 1.91s.

1 ,34 1,67 1. atente J 11116 1, 1920.,

3 SHEETS-SHEET 3- v 47m EY- INVEIITOR 1 gg UNITED oFFicE.

APPARATUS FOR MANUFACTURING PISTON-RINGS.

Specification of Letters Patent.

Application filed October 12, 1918. Serial No. 257,843.

To all whom it may concern:

Be it known that I, FREDERICK RAY, a citizen of the United States, residing at Short Hills, Essex county, State of New Jersey, have invented certain new and useful Improvements in Apparatus for Manufacturing Piston-Rings, of which the following is a specification.

This invention relates to an apparatus for manufacturing piston rings of concentric form, that is to say, uniform cross-section, which are split and then hammered or otherwise acted upon on their inner circumferences with localized blows or pressure definitely varied at the different sections of the ring so as to cause the same to open and, when compressed again to circular form in a cylinder, to exert approximately equal reaction upon the confining wall at all points, as compared with concentric rings which have had a piece'cut out and have not been hammered, which are distinctly non-uniform in their outward pressure under working conditions.

Concentric equal pressure rings can be produced by taking ring blanks of the diameter of the cylinders which they are to enter (plus a slight excess for finishing on the outer circumference.) splitting them at one point without material removal of the metal, then clamping them by pressure applied to their side faces in a suitable chuck, and rotating this chuck with the ring slowly or in a step-by-step manner relatively to a triphammer mechanism with a suitably shaped point, preferably a rounded or a narrow or a wedge-shaped point, within the'ring, the lift of the hammer and therefore the intensity of the blows being automatically varied in the hammering of each ring through the action of a control cam turning with the chuck.

I have demonstrated, that a ring to exert truly uniform reaction, when compressed and retained in circular shape, as under working conditions, must contain stress moments in all its sections varying in accordance with the expression, 1cos a, where a is variable, being the angle between the split and any section of the ring.' Acting upon the theory that the bending moments existing in the completed ring when compressed back to circular form correspond to the stress moments which were set up .in the ring blank durin the hammering and opening operation, fhave prov ded a control cam which embodies the l-cos a law, that is to say one wherein the elevation of the hammer corresponding to every point of the cam varies, as the expression 1cos a, a being the angle between that point and the point on the cam which corresponds to the split of the ring. Cos a is the abbreviation for the cosine of said angle.

Theoretically such a cam will produce substantially perfect rings, provided the hammering or pressing point is absolutely sharp, in which event, evidently, thestress moment is proportional to the intensity of the blow or pressure. The edge cannot, however, be absolutely sharp, and must become duller with use, and in some instances rounded points are employed. Actually, I have discovered that the real law is that the bending moments set up are in ,proportion to the intensities of the blows plus a constant, and that the value of this constant depends upon the sharpness or dullness or shape of the point. Thus, in order to hammer a piston ring so as to give uniform radial pressure at all points of the circumference when in use, it is necessary to vary the intensities of the blows in accordance with the expression 1 cos a plus a constant.

If the hammer blow is caused by a falling weight, the intensity of the blow is in proportion to the height or drop of the weight. In such case it apparently follows from the foregoing that the shape of the control cam should be such that the height of fall of the weight would vary in accordance with the law, height varies as 1c0s a plus a constant. For such a hammer to operate satisfactorily it would be necessary for the point to he kept always in exactly the same condition of sharpness or it would be necessary to preserve its shape if other than .a sharp point were used, which would be exceedingly diflicult from a practical standpoint.

Hammers are also in use in which a large portion of the intensity of the blow is due to the recoil of a spring. In such a case, if the spring is entirely expanded and exerts no pressure whatever when the hammer strikes the ring, then the intensity of the blow due to the compression of the'spring is'directly in proportion to the amount of such compression (or tension). rection of the compression of the spring has a vertical component, then the intensity of the blow, due to the weight of the moving If the di-- Patented June 1, 1920.

a plus a constant.

parts, being proportional to the lift, is also in proportion tothel amount of compression of the spring and consequently the whole intensity of the blowis in proportion to the amount of compression. Therefore to hammer a ring with such a machine, to give uniform radial pressure at all points of the circumference under conditionso'f use, the cam would apparently have to be so shaped as to cause the compression of the spring to vary in accordance with the expression, compression varies proportionately to 1 cos Such a cam would only be suitable for a hammer point in but a single condition of sharpness.

. I have found that as these hammers are run, the hammer point gradually dulls and the value of the constant changes. I have also found that different hammer points require different constants. This would require that the shape of the cam be changed from time to; time and would be very objectionable from a commercial standpoint. I have also found that it is possible to overcome this difficulty by properly adjusting the spring which furnishes a portion or a whole of the energy required to drive the hammer. Thus I can utilize a single cam which is laid out so as to cause the compression of the spring to vary in accordance with the law, compression varies propor-Z tionately to 1.cos a, and by providing means for adjusting the amount of the initial compression of the spring while the hammer point is in contact with the ring, I can add any desired constant to the intensities of the blows. A perfectly elastic spring if compressed from its free state ofl'ers a resistance to the compression exactly in proportion to. the amount of the compression. If, however, this same spring is subjected to an initialcompression, which will give any desired reaction, then on further compression from this point of initial compression the total reaction is in proportion to the amount compressed plus the initial compression. Thus in a hammer pro vided with such a spring and with means for appropriately varying its initial compression and with a cam laid out according to 'the law of compression varies proportionately to 1cos a, by giving the spring a proper initial compression when the hammer point is resting upon the ring the intensity of the blows will vary as, 1cos a due to the shape of the cam, and plus a constant, due to the initial compression of the spring; but the bending moments set up in, the ring, and consequently the stress moments in the ring when in use, will vary according. to the first law (1cos a) and not according to the second or modified law.

By this means I am, therefore, enabled to hammer a ring to give uniform radial pressure at all points of its circumference by using a single cam and adjusting the initial compression of the-spring to suit the shape of the hammer point. Likewise as the hammer point varies, due to wear, I can compensate for this variation by further adjustment of'the initial compression of the spring.

In the manufacture of such rings, it is necessary to hammer rings of different diameters and rings of the same diameter giving different intensities of pressure. This requires that the intensity of every blow delivered to some rings shall be greater or less than the intensity of the corresponding blows delivered to other rings, without changing the law of the variation of the blowsrelative to the ring. In the case of a welght-loaded hammer this could be accom-' plished by-vchanging the weight of the hammer. In the case of a spring-loaded hammer, such as shown in the drawing, the same uated exactly to the required amount.

oyercome this difficulty by using a single spring of such length and strength or stiffness that-when the whole of the spring is permitted to deliver the blow, the intensity of the blow will be as small as normally required. Then by means of a clamp nut, which is provided with an internal thread so that it will screw over the coils of the spring, as an ordinary nut screws over the thread on a-bolt, I am enabled to shorten up the. effective or active part of the'spring to any desired amount, and thus increase its resistance to compression, and thus increase the intensity of. the blows to any desired extent within the limits" of the strength of the spring. This follows from the fact that a spring ofa given size compressed a givenv linean amount exerts a resistance to the compression inversely in pro ortion to the total original length of the spring. Thus of each blow by simply sliding the nut lengthwise and clamping without turning, thus giving any desired initial compression to that rtion of the spring in use. I am thus ena led by means of the cam, shaped so as to give a variation to the compression of the spring in accordance with'the law, compression varies proportionately to 1cos a and a spring provided with means for varying both its length and its initial compression, to hammer rings with blows varying in intensity according to the law, intensity varies proportionately to 1cos a plus a constant, but producing bending moments according to the law 1 cos a, and at the same time making the absolute value of the intensities of the blows any desired amount. I- am thus enabled to produce rings of any size giving a uniform radial pressure at all points of the circumference, the magnitude of this pressure being anything desired withmounted on a base 3. The ring a to be operated upon is held in this chuck by removable and interchangeable ring seat and laterally clamping members 4: and 5. The hammer 6 is mounted slidably ona Vertical post guide 7 rising from the base and is prevented from turning laterally by a rear guide-pin 8 depending from a top bracket 9. The hammer, as usual, has a forward projection-extending within the ring chuck and carrying a removable striker 10 having preferably a wedge-shaped point, which is usuallyeither sharp, slightly rounded or sli htly fiattened.

he ring holder is rotated slowly in a step-by-step'manner by a pawl 11 pivoted at 12 on a vertical rod 13 which is mounted sli'da'bly in the frame of the machine. The pointof this pawl engages ratchet teeth 14, which are formed all the way around the circumference of the chuck, and is pressed into engagement with these teeth by a spring 15 which is interposed between a collar 16 fixed to the rod 13 and another collar 17 which is slidable thereon to press against the base of the pawl. The rod 13 is repeatedly raised by an eccentric 18 on the main driving shaft 19 of the machine, this eccentric acting upon the lower end of the rod.

through the interposition of a lever 20. A spring 21 is compressed by the raising of the rod and restores the same to its lower posi tion after each elevation.

The hammer is raised and' permitted to fall by a tapered tripping cam 22, which is splined on the shaft 19 so as to be movable lengthwise but not rotatably with reference thereto. This cam cooperates with the lower end of a reciprocatory rod 23, which is guided in the interior of the post 7 and united with'the hammer 6 by a cross-pin 24 working in slots 25 in the sides of the hollow post. The position. of the cam 22 on the shaft, and therefore the degree to which it lifts the hammer,- is automatically varied during the hammering of each ring by the action of a control cam 26 which is secured to the chuck 1 by means of screws 27.

The shifting of the cam 22 is effected 'through the intermediate agency of a downwardly extending lever 28, which is pivotally fulcrumed at 29 at its upper end on the frame and is provided at its lower end with a yoke 30 pivoted to a fork 31, which embraces a'grooved collar 32 on an extension 33 of the tripping cam. A roller 34 mountedon an intermediate portion of the lever 28 bears against the periphery of the control cam 26. A spring 35 connected with the lever 28 holds the roller 34 against the control cam and urges the lever and tripping cam in one direction while the control cam acts to move them in the opposite direction. Slots 36 in the control cam, be-

neath the heads of the screws 27, enable this cam. to be adjusted rotatably with respect to the ring holder.

The cam 26, it will be understood, is to be made in accordance with the expression, compression varies as 1,-cos a, a being a "ariable and representing the angle between any pointon the periphery of the cam and the low point I), which corresponds to the split in the ring. The exact shape of the cam itself depends upon the levers, etc. This does not mean that the point .7) is adjacent the split in the ring. This may or may not be so, according to the particular arrangerangement may be provided as in VVasson Patent 1,016,380, so that the machine is stopped automatically when the point I) returns opposite the roller 34 after having completed the circuit.

Coming now to the more particular novelty of the present invention, it will be observed that a helical spring 37 is interposed between the top of the hammer 6 and a fixed upper abutment 38. As heretofore explained, this spring should be of sufficient length to enable the hammer to deliver the lightest blows with which the machine is designed to operate.

As stated, means are provided for varying the effective length of the spring and thereby changing its stiffness, and for holding it, or not, under initial compression, and for varying the degree of such initial compression. Such means may be varied, but preferably comprise a nut-lock clamp collar 39 made in two halves connected by screws 40,

. as shown in Fig. 3. A set screw 41 passing radially through a threaded aperture in one of the halves of the collar is adapted to bear against the spring 37 in order to hold the spring from turning in the collar. The interiors of the halves of the collar 39 are formed with a spiral groove, like a screw-' thread, to receive the convolutions of the spring. In order to vary the effective length of the spring the locking screw 41 and the screws 40 are loosened and the collar is turned as to be screwed up or down the desired distance on the spring, after which the screws 40 and 41 are again tightened. It will be understood that all that portion of the spring within and above the nut collar is inactive. Consequently the further down on this spring the nut is screwed, the shorter will be the effective spring length and the greater the resistance to compression when the hammer is lifted. Conversely, the farther upward the collar is screwed on the spring, the greater will be the effective length and the. lighter will be the blows.

' At any spring length the, active portion of the spring beneath the collar may be placed under any desired degree of initial compression by moving the collar 39 downward without turning it and then looking it by clamping the collar upon the post, by the screws 40, in the new position.

In the diagrams, Figs. 4, 4 illustrate the condition which XlStS with maximum spring length and without initial compression. The inner shaded area m on the control cam 26 indicates the lift of the hammer by the tripping cam 22 as shifted under the action of the control cam. The height to which the hammer is raised varies throughout the hammering of each ring, but is the same in amount at corresponding points in the hammering of all the rings and under all adjustments of the spring. Thus the shaded area 00 is the same in Flgs. 4*, 5 and 6. The outer shaded area y in Fig. 4: represents the intensity of the blows, due'to the force of gravity plus the recoil of the spring. In Fig. 5 the effective length of the spring has been shortened but it has not been placed under initial compression. Consequently the shaded area y representing intensity of blows, is wider in Fig. 5 than in Fig. 4, because of the greater stiffness of the spring. In Fig. 6 the effective length of the spring has been shortened and in addition the active part of the spring has been placed under initial compression by sliding the collar 39 straight downward, as heretoforedescribed. Consequently in Fig. 6' there is a supplementary shaded area 3 of uniform width throughout the circle, which represents the constant added by the initial compression.

The procedure of hammering these rings consists in placing a blank in the chuck of the hammer provlded with a cam made in accordance with the above law for the cam, then adjusting the length of the spring by means of the nut to some length which the operator considers to be approximately correct for the desired intensity of pressure, then giving the spring a slight initial compression, the amount also being a matter of judgment. The ring is then hammered and tested by means of the gaging device of my copending application Serial No. 93,904, filed April 25, 1916. The-scale reading of the gaging device, divided by the radius of the ring, gives the pressure per inch of circumference and .if this pressure is too great the nut is screwed upon the spring, so that a longer section" of the spring becomes operative. If the intensity is too small the spring is correspondingly shortened. The circularity of the ring is then tested. If the diameter of the ring passing across the points is found to be shorter than the diameter perpendicular thereto, slightly more additional initial compression is given to the spring by sliding the nut down sli htly without turning and then clamping. f the points are lon then the initial compression is reduced. If one point is lon er than the other then the cam is rotated s ightly relative to the ringso that the intensity of the hammer blows on that side of the rin will be slightly decreased, and the intenslty of the hammer blows on the other side will be slightly increased. After these adjustments are made as well as possible from the indications of the gage, a second ring is hammered and again is tested on the gaging device. Ordinarily it re uires but a few trials of this sort to set t e hammer so that a substantially perfect ring is produced. .The hammer is then .placed in operation and from time to time a ring is tested on the gaging device, and if necessary the initial compression of the spring is changed slightly to allow for any dulling or change By this bination of ring-supporting means, a pointed member to act upon theinner circumference of the ring, a spring for energizing said member, means for automatically varying the force of the spring as the member acts upon different sections of the ring, and means for adjusting the effective length and the initial compression of the spring.

2. A machine for hammering piston rings comprising the combination with a ring chuck and hammer mechanism, of a spring for supplying energy to the hammer, a cam automatically controlling the compression ofthe spring at the different sections of the ring, and means for adjusting the effective length and initial compression of the spring.

3. In a machine for hammering piston rings having a ring chuck, hammer mechanism and a spring for supplying energy to the hammer mechanism, the combination of means for automatically varying the com pression of the spring at the different sections of the ring in accordance with a fixed law, and means for producing adjusted initial compression of the spring so as to add a constant of such value to the intensities of the blows as to enable the hammer mechanism to set up stress moments in the ring in accordance with the law.

4. In a machine for hammering piston rings having a ring chuck, hammer mechanism and a spring for supplying energy to the hammer mechanism, the combination of means for automatically varying the compression of the spring at the different sec tions of the ring in accordance with a fixed law, and means for either or both adjusting the effective length of the spring so as to vary the intensities of the blows andadj usting the initial compression of the spring so as 'to add a constant intensity to the intensities of the blows.-

5. In a machine for hammering piston rings having a ring chuck, hammer mechanism, and a spring for supplying energy to the hammer mechanism, the combination of cam means for automatically varying the compression of the spring at the difierent sections of the ring in accordance with a fixed law, and means for securing adjusted initial compression of the spring, whereby constants 0 such value may be added to the 'intensities of the blows as to enable the hammer mechanism .to produce rings of uniform reaction. 1

6. In a machine for hammering piston rings having a ring chuck, hammer mechanism, and a spring for supplying energy to the hammer mechanism, the combination of cam meansfor automatically varying the compression of the spring during the hammering of each ring, and means for adjusting the effective length and the initial compression of the spring. a

7. In a hammering machine, the combination with a ring chuck, hammer mechanism, a spring for supplying energy to the hammer mechanism, and cam means for automatically varying the compression of the spring at the different sections of the ring, of a clamp adapted to engage the spring, and means whereby said clamp may be shifted in the direction of the axis of the spring either relatively thereto or when in holding engagement therewith.

8. In a hammering machine, the combination with a ring chuck, hammer mechanism, a spring for supplying energy to the hammer mechanism, and cam means for automatically varying the compression of the spring at the different sections of the ring, of

a support inside the spring and a nut-lock clamp surrounding and engaging the convolutions of the spring, and means whereby the clamp may be anchored at various positions along the support and may be shifted lengthwise thereof either with or without affecting the compression of the'spring.-

9. In a machine for hammering piston rings having a ring chuck, hammer mechanism and a spring for supplying energy to I the hammer mechanism, the combination of acam which is laid out so as to cause the compression of the spring to vary in accordance with the law, compression varies proportionately to one minus the cosine of the angle through which the cam turns and means for producing adjusted initial compression of the spring so as to add a constant of such value to the intensities of the blows so as to enable the hammer mechanism to set up stress moments in the ring so as to produce rings of uniform reaction.

In testimony whereof I have signed my 

